1. Field of the Invention
The invention relates to a measurement device and a measurement method at a lifting means, in particular at lifting rope subjected to load for hoisting machines.
2. Brief Description of the Background of the Invention Including Prior Art
A measurement device for capturing the rope deflection for a loading apparatus, in particular for an automatic loading operation, is known from the German Printed Patent Publication DE-OS 2,115,587. The rope deflection is captured in the motion direction of the loading device and of the crane trolley. The loading device comprises substantially a movable lifting device, which is connected via several lifting ropes with a gripper device for a container. The measurement device is disposed at one rope end at the lifting device and comprises essentially two bows supported like a universal joint suspension on axes offset by 90.degree.. The bows surround the vertical lifting rope with a ring. A deflection entails a pivoting motion of the universal joint axes. The pivoting motion is captured via gear segments by potentiometers. The potentiometers are connected to a signal processing device for determining the rope deflection.
This measurement device appears to be disadvantageous, since the accuracy of the determination of the rope deflection based solely on the linearity deviation of the potentiometers is insufficient for an application with, for example, automatic pendulum balancing control systems.
In addition, measurement devices, operating according to the above described measurement principles, are known within the organization where the inventor is active. These known measurement devices are disposed at a tensioned measurement rope furnished in addition to the lifting ropes. The measurement rope is retained under tension by an idling motor. The structural expenditure for this measurement device is disadvantageously increased by the additional measurement rope in connection with the idling motor.